This work is licensed under a Creative Commons Attribution 2.5 License.
This means you may use it for any purpose, and make any changes you like. All I ask is that you include a link back to this page in your credits (although a giant link on every page of your website really isn't needed, contact me to discuss specifics).
The icons can also be used under Creative Commons Attribution 3.0 License (Hi Debian folks!) with the following requirements:
As an author, I would appreciate a reference to my authorship of the Silk icon set contents within a readme file or equivalent documentation for the software which includes the set or a subset of the icons contained within.

Screenshot:

Note: unfortunately, this set contains not too many icons for table operations.